Piston expander



Malth 7, 1939. c Q'B 2,150,062

PISTON EXPANDER Filed Oct. 2, 1934 r-"lE nl; F1E| E I T I INVENTOR. C'fiar/es f Jo #5/0/7 A TTORNE Y Patented Mar. 7,1939 I j UNITED. STATES PATENT OFFICE PISTON EXPANDER 1 Charles F. Johnston, ,wm, Calif. Application October '2, 1934; Serial 740,490

180laims. (01." 309-12) The invention relates to means arranged for Figure 5 is a perspective view of theexpander. use in connection with a piston forholding the a Figure 6 is an enlarged'view taken inside of skirt of the piston in expanded relation wherethe piston and showing a modified form of my by the latter may compensate Ior the wearing invention.

5 inthe cylinder walls and resulting in what is 4 Figure '7 is a perspective view of the modified 5 generally known as piston slap. form of expander shown'in Figure 6.

An object of the invention is to provide a As illustrated in Figures l to 5 of'the drawing, means of the character described which will the expander member 2 of my invention is aroperate directly on the longitudinal slot provided ranged for positioning on the inside of a piston 10 in the piston skirt for expanding the circum- 3 such as used in an internal combustion engine. 10 ference of the skirt and which will afford a de- More specifically the member 2 is arranged for gree of resilient flexibility for enabling the piston positioning within the portion 4 of the piston,' to vary in diameter during the course of its usually termed the skirt and which includes movement to snugly conform'to minor variations the sides of the piston, extending to the open in the cylinderbore; end 6. 15

Another object of the invention is 'to provide In the type of pistonwith which the means a means of the character described which will iof my invention is arranged for use, the skirt be comprised of a single one piece-member, so portion 4 is provided with a longitudinal slit designed as to afford a maximum resilience and 1 which extends from a po t adjacent the n strength for the amount of material used, whereretaining portion 5 0f the piston to the end 5. 20

by the same will be of minimum size and weight At the inner end of the slit, that is adjacent the and of simple and inexpensive manufacture. portion 5,-the slit is communicated witlr'a cross A further object of the invention is to provide or circumferentially extending slit 8 which pera means of the character described which will mits the skirt po a a nt e slit 1 of a 25, afford the desired expansion of the piston skirt; limited outward expansion. for the full length thereof without requiring any In accordance with the present invention, 1 departure from the design of the conventional provi a meahs Which is arranged to eng e d type of piston. a f ,9 rectly in the slit 1 for spreading the same and still a further object of the invention is to for effecting an expansion of the skirt portion of provide a piston skirt expanding means which the piston. As here shown, the means comprises 30 maybe absolutely locked in bperative position a flat spring member ll formed with opposed leg I in the piston without requiring the provision of portions 12 which are interconnected at an end any attaching parts to the piston or the use of by a loop portion 13. In the embodimentshown any attachments between the piston and the in Figures 1 to 5, the free ends 15 of leg portions expander. are spaced somewhat so as to resiliently resist r The invention possesses other objects and 'feabeing brought together and are formed with outtures'of advantage, some of which, with the standing loss 14 which are a ed f en a foregoing, will be set forth in the following 1 8 in the 810i? 1 S0 tw n sprung thereinto, description of the preferred form ofthe inventhe member II will be strained to set up an e tion which is illustrated in the drawing accompending action on the piston skirt. In order that 40 panying and forming part of the specification. the member may be positively locked against It is to be understood, however, that variations loosening from an engaged position in the piston, in the showing madeby the said drawing and, the latter is preferably drilled at the slit 1,-predescription may be adopted within the scope of paratory to insertion of the xpander, 50 as to the invention as set forth in the claims. define the skirt at opposite sides of the slit op- 45 Referring to said drawing: posing seat or socket portions I6 for engagement Figure 1 is a side elevation of a piston with with the lugs l4. Also the lugs are preferably the expander of my invention applied thereon. flared o w y from the plane 01 t leg sides Figure 2 is a vertical sectional view. showing and formed with sharply defined outer corners the inside of the pistonof Figure 1 and the which cause the lugs, under the urge oi the attachmentioi my expander thereto. strained member, to bite or cut into, and'lock Figure 3 is an enlarged outside view similar to themselves in, the socket portions 16. It de- Figure 1. v sired and as perhaps best seen from Figures 5 and Figure is a sectional view taken substantially 6 the sides of the leg portions may be convergenton the plane of the line 44 of Figure 1. 1y tapered towards the free ends thereof so as to reduce the overall transverse extension of the V blank of material with a minimum of material wasted in the forming of the lugs and at the same time utilizing the wider folded end of the blank for strengthening the expander.

As a particularly important feature of the invention, the side or leg portions of the expander are bowed over their length so as to converge from the interconnecting loop portion l3 into closely opposed position at portions l1 intermediate their ends and then diverge into well spaced position at the free ends l5 thereof. Thus on drawing the free ends together, the portion ll will be moved into contact to provide on further approachment of the ends for the setting up over the length of the leg portions, a double cantilever spring *action which is produced, as will be understood, by reason of the attachment of the ends at the loop portion l3 and the fulcruming of the legs on the intermediate portions II. By reason of this double cantilever action a ye'ry considerably greater force may be developed for the short movement required than could otherwise be obtained and as a result a considerably smaller. and lighter member may be used.

Amodified form of the invention has been shown in Figures 6 and 7 wherein the leg portions l2 of the expander are bowed slightly to space the intermediate portions thereof but to engage the free ends I5. The lugs H are provided 'on intermediate portions of the legs whereby their movement together is resiliently resisted by a flexing of the legs between their ends. In this manner not only are the legs stiffened by their engagement at the interconnecting loop portion l3 but also by their engagement at their free ends l5. Thus the stress set up in the expander by reason of a drawing together of the lugs M will be distributed over the full length thereof with the result that, as in the case of the first described embodiment, a maximum expansion force may be obtained for a minimum size and lightness of material.

Iclaim:

1. In an expander for a piston having the skirt portion thereof provided with a longitudinal slit recesses in the opposite side facesof said slit opening into said slit, a generally U shaped fiat spring member provided with opposed longitudinal leg portions adapted for mounting at the inner side of said piston in substantially parallel relation to said slit and having transverse projections arranged to be sprung into said recesses for circumferentially expanding said piston.

2. In an expander for a piston having the skirt portion thereof provided with a longitudinal slit,

a flat spring folded to define a pair of opposed leg portions, projections provided on said leg'portions adjacent the free ends thereof and arranged to be sprung into said slit for spreading said slit, said leg portions being bowed over their length so as to contact and provide a fulcrumifig support for each other intermediate their lengths. 3. In combination with a piston having the 'skirt portion thereof formed with a longitudinal slit and provided with opposed recesses opening to said slit, an expander having longitudinal sides arranged for mounting opposite said slit at the inner periphery of said skirt and each pro.- vided with an offset portion arranged for en- "I gagement in said for spreading said slit.

4; In combination with a piston having the skirt portion thereof formed with a longitudinal slit and provided with opposed recesses opening.

to said slit, a spring member having longitudinal sides arranged to engage the inner periphery of said skirt at opposite sides of said slit and pro- .vided with portions thereof arranged for'engagement in said recesses for spreading said slit.

5. In an expander for a piston having the skirt portion thereof formed with a longitudinal slit, .a fiat spring member folded to provide a pair of opposed side portions, said side portions being bowed to space the intermediate portions thereof and arranged on drawing together to contact adjacent the free ends thereof, and projections carried by said intermediate portions and arranged to be pressed towards each other and sprung into said slit for expanding the piston.

6. In an expander for a piston having the skirt portion thereof formed with a longitudinal slit and provided with opposed curved recesses in the opposed skirt sides defining said slit, a

spring having spaced projections arranged to be sprung into said recesses for spreading said slit,

said projections being formed with sharply defined corners arranged to pierce into the curved walls of said recesses.

7. In an expander for a piston having the skirt portion thereof formed with a longitudinal slit and provided with opposed curved recesses in the opposed skirt sides defining said slit, a spring of elongated form having, spaced projections arranged to be sprung into said recesses for spreading said slit, said projections being flared longitudinally of said spring and formed with sharply defined corners arranged to pierce into the curved walls of said recesses to resist withdrawal of said portions therefrom.

8. An expander for a piston having a longitudinal slit in the skirt portion thereof comprising, a fiat spring member formed with spaced longitudinal sides interconnected at an end, and a transverse projection on each of said sides adjacent the. other end thereof adapted upon positioning of said sides longitudinally within said piston to engage in said slit for spreading same,

each of said sides being progressively narrowed in width from said first to said second end and being of a width at said projections substantially equal to the width of said opposite-end.

9. In an expander for a piston having the skirt portion thereof provided with a longitudinal slit to permit expansion thereof, a spring member comprising, a pair of opposed sides supported one on the other at one point and connected at another and having spaced portions arranged to be sprung into said slit to engage and spread the opposed faces of said slit.

10. A piston having the skirt portion thereof formed with a longitudinal slit and provided with curved concave recesses at opposite sides of said slit in combination with, a ring member comprising, spaced compressible portions adapted to be sprung into said recesses for expanding said skirt and having sharply defined corners adapted to pierce the curved walls of said recesses to prevent relative turning.

11. In combination: a piston comprising a head portion and opposed f thrust faces, one of said thrust faces having a Jcngitudi'nal slot therein forming opposed edge faces, each of said edge faces having at least one notch therein extend ing transversely of said longitudinal slot; and a sheet metal expander comprising a resilient body having portions thereof in contact with the inner surface of said slotted thrust face, said body also having a plurality of retaining lugs extending laterally therefrom, one of said retaining lugs being seated in each of said notches.

12. A piston having a. longitudinal slit in the.

skirt thereof in combination with an expander comprising, a body ofresilient sheet metal folded to provide opposite members with free end portions adapted to be sprung towards each other and inserted in said slit to provide on release and expansion of said portions for theexpansion of said slit and piston, said body being formed to provide a support for said members adjacent said portions to increase .the resilient resistance to-the springing of said edge portions together and to increase the resilient expansion of said portions against the sides of said slit.

13'. A piston having a longitudinal slit in theskirt thereof in combination with-an expander comprising, a body having spacedopposed slitface engaging portions adapted for contraction towards each other for insertion into said slit and connected remotely from each other to reskirt thereof in combination with an exp'ander' comprising, a body having spaced opposed slitface engaging portions adapted for contraction towards each other for insertion into said slit and l connected remotely from each other to resiliently resist said contractiomsaid body also provided with hearing portions adiacentsaid first por-' tions and operating to resiliently hold apart said first portions and coacting with said connection to increase the resilient resistance to contraction of said first portions. H

15. In an expander for a piston having a longitudinalslitintheskirtthereofandarecessin at least one of the opposed facesof slit extending entirely through the-wall of said skirt, a spring memberadapted for mounting at the inner side of said skirt and having transversely projecting portions adapted for springing together to a size permitting insertion-thereof into saidslit at said recess in a radial direction 'relative to said piston.

16. In combination, a piston comprising a head portion and opposed thrust faces, one of said thrust faces having a longitudinal slot therein forming opposed edge faces, each of said edge faces being formed with a recess extending entirely through the wall thereof, and opening to said slot, and an expander comprising a resilient body'adapted for positioning atthe inner side I of said slotted thrust face and having slot face engaging portions adapted for insertion into said recesses and being contractable towards each other to a circumferential width no greater than the circumferential spacing of said recesses to enable insertion of said portions in to said recesses in a radial direction relative to said piston.

17:1n an expander for a piston having the skirt portion theieof formed with a longitudinal slit, an elongated member adapted for mounting in the interior of said skirt adj centsaid'slit with its length in substantially par el relation there-. to, said member being curved lengthwise'and pro- .vided with'a plurality of laterally extending lugs adapted for springing into said slit for spreading said skirt;

18. A piston having a skirt portion formed with 'a longitudinal slit and provided with a plurality of recesses in the opposededge faces of said slit, and an elongated member adapted for mounting in the interior of said skirt with its length'in substantially parallel relation to said slit and for engagement with the wall of said skirt at said slit, said member being curved lengthwise and provided with a plurality of retaining lugs at the opposite ends of said member engageable in said I recesses.

canines r. Jomis'rom I 

